Apparatus for dry galvanizing wire



July 30, 1935. A. F. BRA DLEY 2,009,573

APPARATUS FOR DRY GALVANIZING' WIRE I Filed June 21, 1933 Patented July so, 1935 UNITED STATES APPARATUS non DRY, GALVANIZING Winn Albert F. Bradley, Sterling, Ill., assignor to Northwestern Barb Wire Company, Sterling, 111., a

corporation of Illinois Application June 21, 1933; Serial No. mores 5 Claims. (or. oil-12.2)

This invention relates to a method of and apparatus for dry galvanizing wire and other strip material of ferrous metal, such as iron or steel. .The operation of dry galvanizing is frequently 5 referred to as sherardizing, the principles of which are fairly well known. Sherardizing, however, has not heretofore been satisfactorily applied'to wire, to the best of my knowledge.

.According to the present invention, wire is drawn through a stationary bed of zinc dust, or

other dust containing a large proportion of metallic zinc, at a temperature below that at which fusion and coalescence of the zinc particles results and above that at which cementation oi themetallic zinc with the metal of the wire commences. The wire is drawn continuously through the heated bed of zinc dust and the zinc dust locally agitated so as to increase the contact of the dust with the wire and effect the desired degree of sherar during a single travel of the wire through the bed.

It is therefore an important object of this invention to provide a relatively inexpensive and vemcient method of sherardizing strip material,

" such as wire; and to provide an apparatus particularly well adapted lot: the carrying out of such method.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawing.

This invention (in a preferred form) is illustrated in the drawing and hereinafter more fully described.

On the drawing:

Figure l is a longitudinal, broken' sectional view oi apparatus embodying the principles oi my invention and suitable for carrying out my method of sherardizing wire.

Figure 2 is a sectional view taken substantially on line II- -II of Fig. l with parts omitted.

' As shown on the drawing:

The reference numeral It indicates generally a i'urnace or retort supported upon legs or standards H which may be suitably braced by transverse angle irons l2 and I3 andinclined angle irons 14. The furnace or retort i is provided with a flre box it extending the full length thereof. Said furnace may be suitably tired as by means of oil or the like introduced through a 5 nozzle l6 positioned at an opening il in one end 55 ing or the tire box I! and to divide the fire box from an upper chamber 2i that is substantially closed from the air by means of a top plate 22, side platestt and. 26, a front plate 25 and a rear plate 25. Said front and rear plates 25 and 26, respectively, are provided with aligned apertures 5- ll and M, respectively, through which strands of wire 29 or other strip material of ferrous metal may be passed for passage through a bed 36 of zinc dust contained within said chamber 2i. Within said chamber 25 and supported ,from the 10 plate 26 thereof are a plurality of baffles 32 and i353 which are slotted to provide guides for the strands 29 and which also serve toprevent the carrying along of the zinc dust with the strands of wire as they are pulled in the direction indlcated by the arrow in Fig. l. Dependent bames 3d and 35 are likewise supported from the top plate 22 of said chamber 2i to serve the same purpose and. alsoto provide bearings as at it and till, respectively, for shafts 3t.

' Said shafts til extend substantially the full length of the chamber 29 and project through the rear end wall 26 thereof for connection by means of a plate 35) with a rocker arm Ml," Said rocker arm to is mounted about a fulcrum point ll provided by a bracket 52 that extends from a stand is mounted on said top plate 22. An eccentric M1 is suitably mounted on said stand 53 and is connected by means of a link 45 to one end of the rocker arm to. Said eccentric t4 may be so driven by any suitable means (not shown).

Each of the shafts 38 is provided with a plurality of rake-like members 46, fixedly secured at spaced intervals along said" shafts and having downwardly extending tines 41 that dip-below the bed of zinc dust. The positions of the apertures 40 Z'l and 28 and of the dependent tines 41 of the rake-like members 46 ares0 arranged that the strands oi' wire 29 pass between-adjacent tines 41 and in close proximity thereto. Consequently, the reciprocation of the rake-like members 48 etiects a thorough agitation of the zinc dust in the bed 30 with resulting increased contact of the zinc dust with the moving wire strands. The rakelike members 46, together with the bames. 32, I8, 50 34 and 31 substantially prevent the carrying along 01 the zinc dust with the moving wires and alsoprevent the building up of the bed of zinc 5! are provided in metal of the wire being passed through the apthe top plate 22 for introducing additional zinc dust into the chamber 2|.

In operation, the combustion chamber I5 is heated to the desired temperature by the combustion of oil or other fuel introduced through v the opening ll, together with sufilcient air to perature and time of travel of the wire through the bed of zinc dust are so controlled and regulated that the desired degree of sherardizing or dry galvanizing of the wire will be efiected.

The wire may enter the zinc dust bath cold, but is preferably hot. For example, the wire may be passed in at annealing temperatures, around 1400 to 1600" F., and the sensible heat thereof utilized to effect the sherardizing step. The temperature at which proper sherardizing takes lies between about 650 and 750 F. To obtain these temperatures, either the wire or the zinc dust bath, or both, should be heated, the'temperatures to be employed depending in part upon the speed of travel of the wire through the furnace.

It will be understood that instead of an oil or gas fired retort, superheated steam or other fluid heating means, or electrical heating means, may be employed. One of the important features of my invention is the close control of the temperature at which the bed or zinc dust is maintained in order to produce the desired character and degree of cementation of the zinc with the paratus. Another important feature of the invention is the provision of reciprocating agitating means in close proximity to the moving strands of wire, with the motion of the agitating means parallel to the strands of wire. By this means, the forming of voids in the bed of zinc dust or the building up of the bed locally to uncover any portion of the wire strands is avoided and very eflicient contact between the zinc dust and the wire strands is insured.

While the bed of material has been referred to as consisting of zinc dust, it will be understood that commercial blue dust", a byproduct in the usual method of smelting zinc, is a material that is generally used in the sherardizing process. In any event, the term zinc dust" is intended to cover any of the various forms of zinc containing dust that are suitable for sherardizing operation. In general, such dusts contain approximately to of metallic zinc, with 5 to 8% of zinc oxide. As is well known, the use of a mixture of used and new dust, carefully freed from iron and oxide particles, is generally preferred in sherardizing processes.

Temperatures may, of course, be used such that the individual particles of zinc while in contact with the wire or strip material will be at an incipient melting stage, but actual fusing down and coalescing of the particles of zinc must be avoided if the best results aretobeobtalned. The temperature provided depends somewhat upon the composition of the zinc dust used, as well as upon the speed of travel of the wire through the.

furnace, but in general the temperature of the zinc dust bath should be between about 650 and 800 F. As previously pointed out, the bath of zinc dust may be at a lower temperature, or even cold, if the wire is sufliciently hot when it enters the bath.

Air is substantially excluded from the chamber containing the zinc dust in order to prevent oxidation of the metal of the wire or the zinc. This is accomplished by making the apertures 21 and 28, through which the wire strands pass, comparatively small. e

I am aware that many changes may be made and numerous details of construction may be varied through a wide range without departing from the principles of, this invention, and I,

therefore, do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

I claim as my invention:

1. Apparatus for sherardizing wire, comprising a retort having a lower combustion chamber and an upper separate chamber for containing a bed of zinc dust, agitating means mounted in said upper chamber and having fingers extending into said bed of zinc dust, there being apertures in the end walls of said upper chamber for the passage of wires through said bed of zinc dust and means for reciprocating said fingers in directions parallel to said wires.

2. In an apparatus for "dry galvanizing wire, a substantially closed receptacle for containing a bed of zinc dust, the end walls of said receptacle having apertures for the passage of wires therethrough, rakes having tines extending into said bed of zinc dust and in close proximity to said wires and means for reciprocating said rakes.

3. Apparatus for dry galvanizing aplurality of wires in one operation comprising a heating chamber, an elongated treating chamber thereabove in thermal contact therewith adapted to contain a bed of galvanizing dust, means for drawing wires through said chamber, rakes in said chamber and means for reciprocating said rakes longitudinally in the chamber for agitating the bed therein to insure contact of the wires with the bed.

4. Apparatus for sherardizing wire comprising a retort having a lower combustion chamber and an upper chamber sealed therefrom in thermal relation therewith, a plurality of shafts slidably mounted from the top of said upper chamber, a plurality of rakes extending downwardly from said shafts into close proximity with the bottom of said chamber, baiiles mounted in the bottom of said chamber, means for directing a plurality of wires through said chamber adjacent to said rakes and means for reciprocating said rakes longitudinally of said wires.

ALBERT 1". BRADLEY. 

